This is a working overview of Heptapeptide, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-09-17 and is reviewed periodically as new material appears.
The compound has a calculated molecular weight near 751.9 daltons and carries a net positive charge at physiological pH because of its arginine residue. It dissolves freely in water and in common aqueous buffers, and typically appears as a white or off-white lyophilized powder. The amide backbone makes the molecule susceptible to peptidases, which limits oral use and favors intranasal or parenteral routes. Nomenclature in the literature varies: the substance is also described by the sequence abbreviation TP-7 and by a Russian trade designation.
Regulatory status differs sharply by region. Selank holds a Russian marketing authorization, where it is supplied mainly as nasal drops, while authorities elsewhere have not approved it for medical use. Material sold internationally is therefore usually labeled as a research chemical rather than a medicine. Peer-reviewed publications come predominantly from Russian laboratories, and sample sizes are generally small. Whether the compound produces comparable effects under independent, well-controlled replication remains an open question that the broader literature has not settled.
Selank is a synthetic heptapeptide developed in Russia as a structural analogue of tuftsin, a naturally occurring immunomodulatory tetrapeptide. Its sequence, Thr-Lys-Pro-Arg-Pro-Gly-Pro, keeps the tuftsin core at the N-terminus and appends a Pro-Gly-Pro tail. Researchers at the Institute of Molecular Genetics in Moscow synthesized the compound during the 1990s while searching for peptides with combined anxiolytic and immunomodulatory activity. The added tail was intended to resist enzymatic cleavage and prolong the molecule's presence in circulation.
Naming conventions place Selank in the same research family as Semax, another Russian-developed peptide investigated for cognitive effects. The two compounds share a lineage but differ in sequence and in the biological systems proposed as their targets. Semax descends from ACTH fragments, whereas Selank descends from tuftsin. Publications sometimes identify Selank by its full peptide sequence or by laboratory codes rather than one uniform trade name. Because replication outside Russia is limited, reports on its properties are best read alongside the study design and the purity of the material tested.
Selank is a synthetic heptapeptide developed in Russia during the 1990s. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences designed it as a stabilized analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The compound has been studied primarily for its reported anxiolytic and nootropic effects. It remains largely unknown in Western pharmacology and is not approved as a medicine by major regulators such as the FDA or the EMA.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Analog of the tetrapeptide tuftsin |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Reported consistently across pharmacopoeial descriptions |
| Appearance | White to off-white lyophilized powder | Typical form of research-grade material |
| Solubility | Freely soluble in water | Aqueous buffers; poor in nonpolar solvents |
| Typical storage temperature | -20 degrees Celsius | Lyophilized powder; protect from moisture |
Reported pharmacological effects center on reduced anxiety-like behavior in animal models and on measures of memory and learning. Proposed contributing mechanisms include modulation of GABAergic signaling, shifts in monoamine turnover, and changes in the activity of enzymes that degrade neuropeptides. Effects on the expression of genes linked to neuroplasticity have also been described. No single molecular target is widely accepted, and whether the behavioral findings arise from one pathway or several remains an open question.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed as a stabilized analogue of tuftsin, a naturally occurring tetrapeptide fragment derived from the immunoglobulin heavy chain. The additional Pro-Gly-Pro segment at the carboxyl terminus is intended to slow enzymatic cleavage. The compound is usually described in the literature as a synthetic peptide with anxiolytic and cognitive-related activity, a label that reflects a research context rather than an approved therapeutic category.
Development took place at the Institute of Molecular Genetics of the Russian Academy of Sciences, where a series of short peptides were designed in the 1980s and 1990s. Selank was selected from variants of tuftsin that showed resistance to plasma peptidases. Russian regulatory approval covers it as an anxiolytic agent given intranasally. Outside that market the compound is normally handled as a research chemical rather than a medicine, and no widely recognised international pharmacopoeial monograph exists. The name Selank is a coined trade designation rather than a systematic chemical name.
Enzymatic stability motivates the extra three residues at the carboxyl end. Native tuftsin is cleaved quickly by circulating aminopeptidases and carboxypeptidases, which limits its duration of action and its usefulness as a tool compound. Extending the chain with proline-rich segments is a common design tactic because proline constrains the backbone and slows proteolysis. The same Pro-Gly-Pro motif appears in other Russian-developed peptides of the era. Whether the full seven-residue chain is required for activity, or whether it acts mainly as a prodrug releasing tuftsin, remains unresolved.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. Its four N-terminal residues reproduce tuftsin, a tetrapeptide fragment of the immunoglobulin heavy chain, while the C-terminal Pro-Gly-Pro extension is a synthetic addition. The peptide has a molecular mass near 752 daltons and carries a net positive charge at physiological pH because of the arginine and lysine side chains. Published indexes list it under the name Selank and the sequence abbreviation TKPRPGP. Solid-phase peptide synthesis is the standard production route for research quantities.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a structural analogue of tuftsin, a naturally occurring tetrapeptide fragment of the immunoglobulin heavy chain. The added Pro-Gly-Pro tail was intended to slow enzymatic degradation and extend biological activity. In Russia it is registered as an anxiolytic nasal preparation, while regulators elsewhere have not approved it for clinical use.
Proposed mechanisms centre on modulation of the GABAergic system, with reports of altered expression of genes related to GABA-A receptor subunits and changed monoamine turnover. Some studies describe inhibition of enkephalinase, the enzyme that degrades endogenous enkephalins, which may prolong opioid peptide signalling. Effects on brain-derived neurotrophic factor and on cytokine expression have also been reported. These findings come largely from animal models and small human studies, and the precise primary target remains unresolved.
Lyophilized Selank, the dry powder form, is generally stored frozen at minus 20 degrees Celsius or colder for long-term keeping. The solid is hygroscopic and should stay sealed, dry, and protected from light. Once dissolved, the peptide is less stable and is usually held refrigerated at 2 to 8 degrees Celsius for short periods. Repeated freezing and thawing is avoided because it can promote aggregation and loss of activity. Buffers and pH choice also affect how long a solution remains usable.
Solubility behavior is a practical concern for handling. Selank dissolves readily in water and in common aqueous buffers, which simplifies preparation of working solutions. The choice of solvent, ionic strength, and pH can influence aggregation over time, particularly at higher concentrations. Aqueous solutions are typically sterile-filtered before use. Because stability depends on several variables, storage and handling notes should be treated as general guidance rather than fixed rules, and specific values are best confirmed against a certificate of analysis for each batch.
Characterization of Selank in a laboratory setting relies on standard peptide methods. Reverse-phase high-performance liquid chromatography separates the target from related impurities and provides a purity figure, commonly reported as 95 percent or higher. Mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, confirms the molecular mass and helps detect truncation or modification. Amino acid analysis can verify composition when a sequence-level check is needed. These techniques together establish identity and purity for a given lot.
=== Connective tissue proper === Loose and dense connective tissue are distinguished by the ratio of ground substance to fibrous tissue. Loose connective tissue has much more ground substance and a relative lack of fibrous tissue, while the reverse is true of dense connective tissue. Loose connective tissue includes reticular connective tissue and adipose tissue. Dense connective tissue is subdivided into dense regular and dense irregular connective tissue. Dense regular connective tissue, found in structures such as tendons and ligaments, is characterized by collagen fibers arranged in an orderly parallel fashion, giving it tensile strength in one direction. Dense irregular connective tissue provides strength in multiple directions by its dense bundles of fibers arranged in all directions.
According to The Jewish Dietary Laws, the book of kosher guidelines published by the Rabbinical Assembly, the organization of Conservative Jewish rabbis, all gelatin is kosher and pareve because the chemical transformation undergone in the manufacturing process renders it a different physical and chemical substance. Buddhist, Hindu, and Jain customs may require gelatin alternatives from sources other than animals, as many Hindus, almost all Jains and some Buddhists are vegetarian.
24494Pu + 4820Ca → 292114Fl* → 290114Fl + 2 10n This reaction had been tried before, without success; for this 1998 attempt, JINR had upgraded all of its equipment to detect and separate the produced atoms better and bombard the target more intensely. One atom of flerovium, alpha decaying with lifetime 30.4 s, was detected. The decay energy measured was 9.71 MeV, giving an expected half-life of 2–23 s. This observation was assigned to 289Fl and was published in January 1999. The experiment was later repeated, but an isotope with these decay properties was never observed again, so the exact identity of this activity is unknown. It may have been due to the isomer 289mFl, but because the presence of a whole series of longer-lived isomers in its decay chain would be rather doubtful, the most likely assignment of this chain is to the 2n channel leading to 290Fl and electron capture to 290Nh. This fits well with the systematics and trends of flerovium isotopes, and is consistent with the low beam energy chosen for that experiment, though further confirmation would be desirable via synthesis of 294Lv in a 248Cm(48Ca,2n) reaction, which would alpha decay to 290Fl. The RIKEN team reported possible synthesis of 294Lv and 290Fl in 2016 in a 248Cm(48Ca,2n) reaction, but the alpha decay of 294Lv was missed, alpha decay of 290Fl to 286Cn was observed instead of electron capture to 290Nh, and the assignment to 294Lv instead of 293Lv was not certain. Glenn T.
=== In Europe === Chia is considered a novel food in Europe because it does not have "a significant history of consumption within the European Union before 15 May 1997", according to the Advisory Committee of Novel Foods and Processes. Under this rule, chia seeds may be 5% of total matter in bread products. Prepackaged chia seeds must carry additional labelling to inform the consumer that the daily intake is no more than 15 grams and pure chia oil only 2 grams daily. Chia seeds sold in the EU are imported mainly from South American and Central American countries and require inspections for levels of pesticides, contaminants, and microbiological criteria.
The right to freedom of speech and association is guaranteed by Article 14(1) of the Constitution of Singapore, although there are provisions in the subsequent subsection that regulate them. The government has restricted freedom of speech and freedom of the press as well as some civil and political rights. In 2023, Singapore was ranked 129th out of 180 nations by Reporters Without Borders on the global Press Freedom Index. Freedom House ranks Singapore as "partly free" in its Freedom in the World report, and the Economist Intelligence Unit ranks Singapore as a "flawed democracy", the second freest rank of four, in its "Democracy Index". All public gatherings of five or more people require police permits, and protests may legally be held only at the Speakers' Corner. In the Corruption Perceptions Index, which ranks countries by "perceived levels of public sector corruption", Singapore has consistently ranked as one of the least corrupt countries in the world, in spite of being illiberal. Singapore's unique combination of a strong, soft-authoritarian government with an emphasis on meritocracy is known as the "Singapore model", and is regarded as a key factor behind Singapore's political stability, economic growth, and harmonious social order. In 2021, the World Justice Project's Rule of Law Index ranked Singapore as 17th overall among the world's 193 countries for adherence to the rule of law.
Sources: en.wikipedia.org
The First World War was a world conflict, ranging from July 1914 to the final Armistice on 11 November 1918. The Allied Powers, led by the British Empire, France, Russia until March 1918, Japan and the United States after 1917, defeated the Central Powers, led by the German Empire, Austro-Hungarian Empire and the Ottoman Empire. The war caused the disintegration of four empires – the Austro-Hungarian, German, Ottoman, and Russian ones – as well as radical change in the European and Middle Eastern maps. The Allied powers before 1917 are sometimes referred to as the Triple Entente, and the Central Powers are sometimes referred to as the Triple Alliance. Much of the fighting in World War I took place along the Western Front, within a system of opposing manned trenches and fortifications (separated by a "no man's land") running from the North Sea to the border of Switzerland. On the Eastern Front, the vast eastern plains and limited rail network prevented a trench warfare stalemate from developing, although the scale of the conflict was just as large. Hostilities also occurred on and under the sea and – for the first time – from the air. More than 9 million soldiers died on the various battlefields, and nearly that many more in the participating countries' home fronts on account of food shortages and genocide committed under the cover of various civil wars and internal conflicts. Notably, more people died of the worldwide influenza outbreak at the end of the war and shortly after than died in the hostilities.
== Regulations == In 1961 phenoperidine was added to the 1931 Convention for Limiting the Manufacture and Regulating the Distribution of Narcotic Drugs by the World Health Organization via the Single Convention on Narcotic Drugs. In the US it is classified as a Drug Enforcement Administration (DEA) Schedule I controlled substance opiate with a corresponding code 9641.
An early-20th-century form of quackery was the treatment of maladies in a radiotorium. It was a small, sealed room for patients to be exposed to radon for its "medicinal effects". The carcinogenic nature of radon due to its ionizing radiation became apparent later. Radon's molecule-damaging radioactivity has been used to kill cancerous cells, but it does not increase the health of healthy cells. The ionizing radiation causes the formation of free radicals, which results in cell damage, causing increased rates of illness, including cancer. Exposure to radon has been suggested to mitigate autoimmune diseases such as arthritis in a process known as radiation hormesis. As a result, in the late 20th century and early 21st century, "health mines" established in Basin, Montana, attracted people seeking relief from health problems such as arthritis through limited exposure to radioactive mine water and radon. The practice is discouraged because of the well-documented ill effects of high doses of radiation on the body. Radioactive water baths have been applied since 1906 in Jáchymov, Czech Republic, but even before radon discovery they were used in Bad Gastein, Austria. Radium-rich springs are also used in traditional Japanese onsen in Misasa, Tottori Prefecture. Drinking therapy is applied in Bad Brambach, Germany, and during the early 20th century, water from springs with radon in them was bottled and sold (this water had little to no radon in it by the time it got to consumers due to radon's short half-life).
=== Pharmacology === A large class of drugs are enzyme inhibitors that bind to enzymes in the body and inhibit their activity. In this case it is the drug-target residence time (the length of time the drug stays bound to the target) that is of interest. The residence time is defined as the reciprocal value of the koff rate constant (residence time = 1/koff). Drugs with long residence times are desirable because they remain effective for longer and therefore can be used in lower doses. This residence time is determined by the kinetics of the interaction, such as how complementary the shape and charges of the target and drug are and whether outside solvent molecules are kept out of the binding site (thereby preventing them from breaking any bonds formed), and is proportional to the half-life of the chemical dissociation. One way to measure the residence time is in a preincubation-dilution experiment where a target enzyme is incubated with the inhibitor, allowed to approach equilibrium, then rapidly diluted. The amount of product is measured and compared to a control in which no inhibitor is added. Residence time can also refer to the amount of time that a drug spends in the part of the body where it needs to be absorbed. The longer the residence time, the more of it can be absorbed. If the drug is delivered in an oral form and destined for the upper intestines, it usually moves with food and its residence time is roughly that of the food. This generally allows 3 to 8 hours for absorption.
=== Allosteric site transporter substrates === Alternatively, some reuptake inhibitors bind to allosteric sites and inhibit reuptake indirectly and noncompetitively. Phencyclidine and related drugs such as benocyclidine, tenocyclidine, ketamine, and dizocilpine (MK-801), have been shown to inhibit the reuptake of the monoamine neurotransmitters. They appear to exert their reuptake inhibition by binding to vaguely characterized allosteric sites on each of the respective monoamine transporters. Benztropine, mazindol, and vanoxerine also bind to these sites and have similar properties. In addition to their high affinity for the main site of the monoamine transporters, several competitive transporter substrates such as cocaine and indatraline have lower affinity for these allosteric sites as well. A few of the selective serotonin reuptake inhibitors (SSRIs) such as the dextro-enantiomer of citalopram appear to be allosteric reuptake inhibitors of serotonin. Instead of binding to the active site on the serotonin transporter, they bind to an allosteric site, which exerts its effects by causing conformational changes in the transporter protein and thereby modulating the affinity of substrates for the active site. As a result, escitalopram has been marketed as an allosteric serotonin reuptake inhibitor. Notably, this allosteric site may be directly related to the above-mentioned PCP binding sites.
Sources: en.wikipedia.org
Most industries are located in the industrial-port area north of the estuary and east of the city of Le Havre. The largest industrial employer (2,400 employees) of the Le Havre region is the Renault public company in the commune of Sandouville. The second important sector for the industrial zone is petrochemicals. The Le Havre region has more than a third of French refining capacity. It provides about 50% of the production of basic plastics and 80% of additives and oils with more than 3,500 researchers working in private and public laboratories. Large firms in the chemical industry are mainly in the communes of Le Havre (Millenium Chemicals Le Havre), Montivilliers (TotalEnergies, Yara, Chevron Oronite SA, Lanxess, etc.) and Sandouville (Goodyear Chemicals Europe). A total of 28 industrial establishments manufacture plastics in the Le Havre area many of which are classed as SECESO. There are several firms in the aerospace industry: SAFRAN Nacelles, a supplier to Airbus, Boeing and other commercial air-framers, making jet engine nacelles and thrust reversers, is located in Harfleur and employs 1,200 people from the Le Havre area. Finally, Dresser-Rand SA manufactures equipment for the oil and gas industry and employs about 700 people. In the energy field, the EDF thermal power plant of Le Havre has an installed capacity of 1,450MW and operates using coal with 357 employees. The AREVA group announced the opening of a factory for building wind turbines: installed in the port of Le Havre, it should create some 1,800 jobs.
=== Artificial DNA nanostructures === The success of DNA nanotechnology in constructing artificially designed nanostructures out of nucleic acids such as DNA, combined with the demonstration of systems for DNA computing, has led to speculation that artificial nucleic acid nanodevices can be used to target drug delivery based upon directly sensing its environment. These methods make use of DNA solely as a structural material and a chemical, and do not make use of its biological role as the carrier of genetic information. Nucleic acid logic circuits that could potentially be used as the core of a system that releases a drug only in response to a stimulus such as a specific mRNA have been demonstrated. In addition, a DNA "box" with a controllable lid has been synthesized using the DNA origami method. This structure could encapsulate a drug in its closed state, and open to release it only in response to a desired stimulus.
=== Main cell layers === Cnidaria are diploblastic animals; in other words, they have two main cell layers, while more complex animals are triploblasts having three main layers. The two main cell layers of cnidarians form epithelia that are mostly one cell thick, and are attached to a fibrous basement membrane, which they secrete. They also secrete the jelly-like mesoglea that separates the layers. The layer that faces outwards, known as the ectoderm ("outside skin"), generally contains the following types of cells:
== See also == Biological half-life, the time it takes for a substance to lose half of its pharmacologic, physiologic, or radiologic activity Effective half-life, the effective radioactive half-life in organisms after accounting for excretion Half-life of knowledge, the amount of time that has to elapse before half of the knowledge or facts in a particular area is superseded or shown to be untrue Half a Life (disambiguation)
Sources: en.wikipedia.org
Selank is a synthetic seven-amino-acid peptide modeled on tuftsin, a fragment of the immunoglobulin G heavy chain. It was designed in Russia to combine anxiolytic and immunomodulatory properties in one molecule.
The first four residues of Selank reproduce the tuftsin sequence Thr-Lys-Pro-Arg. A Pro-Gly-Pro extension at the C-terminus was added to slow enzymatic breakdown and extend residence time.
It holds marketing authorization in Russia, where nasal drop formulations are sold. No equivalent approval exists in the European Union, the United States, or most other countries.
Selank is a synthetic heptapeptide designed as a stabilized analog of the natural tetrapeptide tuftsin. It has been investigated mainly for anxiolytic and cognitive effects. It is not an approved pharmaceutical in most countries.